The US was warned of post-war Iraq chaos by Britain

Britain warned the US that Iraq would 'collapse into chaos' if Saddam was toppled, a top secret memo by a former Foreign Office official has revealed.

The document, which was made public today after a bitter battle with the Government, shows the UK didn't view Iraq as a threat as late as June 2002.

Carne Ross, the FCO's former Iraq policy expert at the United Nations, concluded that the alleged threat was exaggerated.

"We would frequently argue, when the US raised the subject, that 'regime change' was inadvisable, primarily on the grounds that Iraq would collapse into chaos".

Mr Ross also reveals that weapons specialist David Kelly told him personally that 'the Number 10 WMD dossier was overstated'.

Dr Kelly committed suicide in 2003 after the Government confirmed he was suspected of being the source of a BBC report criticising the infamous dossier on Saddam's alleged WMD.

Mr Ross's 2004 memo was originally written as private evidence for the Butler Inquiry into intelligence failures leading up to the war.

But the Foreign Office insisted that publishing the memo would be a breach of the Official Secrets Act because he wrote it when he was still an FCO employee.

The gag on Mr Ross has now been lifted after MPs on the foreign affairs select committee decided his evidence was material to their own inquiries.

It points out that Mr Ross was the First Secretary to the UK mission to the UN from 1997 to June 2002. He was responsible for Iraq policy ranging from sanctions to weapons inspections.

Mr Ross writes: "During my posting, at no time did Her Majesty's Government assess that Iraq's WMD (or any other capability) posed a threat to the UK or its interests... I remember on several occasions the UK team stating this view in terms during our discussions with the US (who agreed)."

The memo will fuel the belief that the overnment sexed up its dossier to make the case for war.

It states that none of Mr Ross's colleagues at the FCO and MoD working on Iraq had found new evidence to change their view on the regime's lack of weapons.

"What had changed was the Government's determination to present the available evidence in a different light," it said.